ip6_forward.c revision 1.9
1 /* $NetBSD: ip6_forward.c,v 1.9 2000/02/26 08:39:20 itojun Exp $ */ 2 /* $KAME: ip6_forward.c,v 1.28 2000/02/22 14:04:20 itojun Exp $ */ 3 4 /* 5 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the project nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #include <sys/param.h> 34 #include <sys/systm.h> 35 #include <sys/malloc.h> 36 #include <sys/mbuf.h> 37 #include <sys/domain.h> 38 #include <sys/protosw.h> 39 #include <sys/socket.h> 40 #include <sys/errno.h> 41 #include <sys/time.h> 42 #include <sys/kernel.h> 43 #include <sys/syslog.h> 44 45 #include <net/if.h> 46 #include <net/route.h> 47 48 #include <netinet/in.h> 49 #include <netinet/in_var.h> 50 #include <netinet/ip_var.h> 51 #include <netinet/ip6.h> 52 #include <netinet6/ip6_var.h> 53 #include <netinet/icmp6.h> 54 #include <netinet6/nd6.h> 55 56 #ifdef IPSEC_IPV6FWD 57 #include <netinet6/ipsec.h> 58 #include <netkey/key.h> 59 #include <netkey/key_debug.h> 60 #endif /* IPSEC_IPV6FWD */ 61 62 #ifdef IPV6FIREWALL 63 #include <netinet6/ip6_fw.h> 64 #endif 65 66 #include <net/net_osdep.h> 67 68 struct route_in6 ip6_forward_rt; 69 70 /* 71 * Forward a packet. If some error occurs return the sender 72 * an icmp packet. Note we can't always generate a meaningful 73 * icmp message because icmp doesn't have a large enough repertoire 74 * of codes and types. 75 * 76 * If not forwarding, just drop the packet. This could be confusing 77 * if ipforwarding was zero but some routing protocol was advancing 78 * us as a gateway to somewhere. However, we must let the routing 79 * protocol deal with that. 80 * 81 */ 82 83 void 84 ip6_forward(m, srcrt) 85 struct mbuf *m; 86 int srcrt; 87 { 88 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 89 register struct sockaddr_in6 *dst; 90 register struct rtentry *rt; 91 int error, type = 0, code = 0; 92 struct mbuf *mcopy = NULL; 93 #ifdef IPSEC_IPV6FWD 94 struct secpolicy *sp = NULL; 95 #endif 96 long time_second = time.tv_sec; 97 98 #ifdef IPSEC_IPV6FWD 99 /* 100 * Check AH/ESP integrity. 101 */ 102 /* 103 * Don't increment ip6s_cantforward because this is the check 104 * before forwarding packet actually. 105 */ 106 if (ipsec6_in_reject(m, NULL)) { 107 ipsec6stat.in_polvio++; 108 m_freem(m); 109 return; 110 } 111 #endif /*IPSEC_IPV6FWD*/ 112 113 if ((m->m_flags & (M_BCAST|M_MCAST)) != 0 || 114 IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 115 ip6stat.ip6s_cantforward++; 116 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 117 if (ip6_log_time + ip6_log_interval < time_second) { 118 ip6_log_time = time_second; 119 log(LOG_DEBUG, 120 "cannot forward " 121 "from %s to %s nxt %d received on %s\n", 122 ip6_sprintf(&ip6->ip6_src), 123 ip6_sprintf(&ip6->ip6_dst), 124 ip6->ip6_nxt, 125 if_name(m->m_pkthdr.rcvif)); 126 } 127 m_freem(m); 128 return; 129 } 130 131 if (ip6->ip6_hlim <= IPV6_HLIMDEC) { 132 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard) */ 133 icmp6_error(m, ICMP6_TIME_EXCEEDED, 134 ICMP6_TIME_EXCEED_TRANSIT, 0); 135 return; 136 } 137 ip6->ip6_hlim -= IPV6_HLIMDEC; 138 139 /* 140 * Save at most ICMPV6_PLD_MAXLEN (= the min IPv6 MTU - 141 * size of IPv6 + ICMPv6 headers) bytes of the packet in case 142 * we need to generate an ICMP6 message to the src. 143 * Thanks to M_EXT, in most cases copy will not occur. 144 * 145 * It is important to save it before IPsec processing as IPsec 146 * processing may modify the mbuf. 147 */ 148 mcopy = m_copy(m, 0, imin(m->m_pkthdr.len, ICMPV6_PLD_MAXLEN)); 149 150 #ifdef IPSEC_IPV6FWD 151 /* get a security policy for this packet */ 152 sp = ipsec6_getpolicybyaddr(m, IPSEC_DIR_OUTBOUND, 0, &error); 153 if (sp == NULL) { 154 ipsec6stat.out_inval++; 155 ip6stat.ip6s_cantforward++; 156 if (mcopy) { 157 #if 0 158 /* XXX: what icmp ? */ 159 #else 160 m_freem(mcopy); 161 #endif 162 } 163 m_freem(m); 164 return; 165 } 166 167 error = 0; 168 169 /* check policy */ 170 switch (sp->policy) { 171 case IPSEC_POLICY_DISCARD: 172 /* 173 * This packet is just discarded. 174 */ 175 ipsec6stat.out_polvio++; 176 ip6stat.ip6s_cantforward++; 177 key_freesp(sp); 178 if (mcopy) { 179 #if 0 180 /* XXX: what icmp ? */ 181 #else 182 m_freem(mcopy); 183 #endif 184 } 185 m_freem(m); 186 return; 187 188 case IPSEC_POLICY_BYPASS: 189 case IPSEC_POLICY_NONE: 190 /* no need to do IPsec. */ 191 key_freesp(sp); 192 goto skip_ipsec; 193 194 case IPSEC_POLICY_IPSEC: 195 if (sp->req == NULL) { 196 /* XXX should be panic ? */ 197 printf("ip6_forward: No IPsec request specified.\n"); 198 ip6stat.ip6s_cantforward++; 199 key_freesp(sp); 200 if (mcopy) { 201 #if 0 202 /* XXX: what icmp ? */ 203 #else 204 m_freem(mcopy); 205 #endif 206 } 207 m_freem(m); 208 return; 209 } 210 /* do IPsec */ 211 break; 212 213 case IPSEC_POLICY_ENTRUST: 214 default: 215 /* should be panic ?? */ 216 printf("ip6_forward: Invalid policy found. %d\n", sp->policy); 217 key_freesp(sp); 218 goto skip_ipsec; 219 } 220 221 { 222 struct ipsec_output_state state; 223 224 /* 225 * All the extension headers will become inaccessible 226 * (since they can be encrypted). 227 * Don't panic, we need no more updates to extension headers 228 * on inner IPv6 packet (since they are now encapsulated). 229 * 230 * IPv6 [ESP|AH] IPv6 [extension headers] payload 231 */ 232 bzero(&state, sizeof(state)); 233 state.m = m; 234 state.ro = NULL; /* update at ipsec6_output_tunnel() */ 235 state.dst = NULL; /* update at ipsec6_output_tunnel() */ 236 237 error = ipsec6_output_tunnel(&state, sp, 0); 238 239 m = state.m; 240 #if 0 /* XXX allocate a route (ro, dst) again later */ 241 ro = (struct route_in6 *)state.ro; 242 dst = (struct sockaddr_in6 *)state.dst; 243 #endif 244 key_freesp(sp); 245 246 if (error) { 247 /* mbuf is already reclaimed in ipsec6_output_tunnel. */ 248 switch (error) { 249 case EHOSTUNREACH: 250 case ENETUNREACH: 251 case EMSGSIZE: 252 case ENOBUFS: 253 case ENOMEM: 254 break; 255 default: 256 printf("ip6_output (ipsec): error code %d\n", error); 257 /*fall through*/ 258 case ENOENT: 259 /* don't show these error codes to the user */ 260 break; 261 } 262 ip6stat.ip6s_cantforward++; 263 if (mcopy) { 264 #if 0 265 /* XXX: what icmp ? */ 266 #else 267 m_freem(mcopy); 268 #endif 269 } 270 m_freem(m); 271 return; 272 } 273 } 274 skip_ipsec: 275 #endif /* IPSEC_IPV6FWD */ 276 277 dst = &ip6_forward_rt.ro_dst; 278 if (!srcrt) { 279 /* 280 * ip6_forward_rt.ro_dst.sin6_addr is equal to ip6->ip6_dst 281 */ 282 if (ip6_forward_rt.ro_rt == 0 || 283 (ip6_forward_rt.ro_rt->rt_flags & RTF_UP) == 0) { 284 if (ip6_forward_rt.ro_rt) { 285 RTFREE(ip6_forward_rt.ro_rt); 286 ip6_forward_rt.ro_rt = 0; 287 } 288 /* this probably fails but give it a try again */ 289 rtalloc((struct route *)&ip6_forward_rt); 290 } 291 292 if (ip6_forward_rt.ro_rt == 0) { 293 ip6stat.ip6s_noroute++; 294 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ 295 if (mcopy) { 296 icmp6_error(mcopy, ICMP6_DST_UNREACH, 297 ICMP6_DST_UNREACH_NOROUTE, 0); 298 } 299 m_freem(m); 300 return; 301 } 302 } else if ((rt = ip6_forward_rt.ro_rt) == 0 || 303 !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &dst->sin6_addr)) { 304 if (ip6_forward_rt.ro_rt) { 305 RTFREE(ip6_forward_rt.ro_rt); 306 ip6_forward_rt.ro_rt = 0; 307 } 308 bzero(dst, sizeof(*dst)); 309 dst->sin6_len = sizeof(struct sockaddr_in6); 310 dst->sin6_family = AF_INET6; 311 dst->sin6_addr = ip6->ip6_dst; 312 313 rtalloc((struct route *)&ip6_forward_rt); 314 if (ip6_forward_rt.ro_rt == 0) { 315 ip6stat.ip6s_noroute++; 316 /* XXX in6_ifstat_inc(rt->rt_ifp, ifs6_in_noroute) */ 317 if (mcopy) { 318 icmp6_error(mcopy, ICMP6_DST_UNREACH, 319 ICMP6_DST_UNREACH_NOROUTE, 0); 320 } 321 m_freem(m); 322 return; 323 } 324 } 325 rt = ip6_forward_rt.ro_rt; 326 327 /* 328 * Scope check: if a packet can't be delivered to its destination 329 * for the reason that the destination is beyond the scope of the 330 * source address, discard the packet and return an icmp6 destination 331 * unreachable error with Code 2 (beyond scope of source address). 332 * [draft-ietf-ipngwg-icmp-v3-00.txt, Section 3.1] 333 */ 334 if (in6_addr2scopeid(m->m_pkthdr.rcvif, &ip6->ip6_src) != 335 in6_addr2scopeid(rt->rt_ifp, &ip6->ip6_src)) { 336 ip6stat.ip6s_cantforward++; 337 ip6stat.ip6s_badscope++; 338 in6_ifstat_inc(rt->rt_ifp, ifs6_in_discard); 339 340 if (ip6_log_time + ip6_log_interval < time_second) { 341 ip6_log_time = time_second; 342 log(LOG_DEBUG, 343 "cannot forward " 344 "src %s, dst %s, nxt %d, rcvif %s, outif %s\n", 345 ip6_sprintf(&ip6->ip6_src), 346 ip6_sprintf(&ip6->ip6_dst), 347 ip6->ip6_nxt, 348 if_name(m->m_pkthdr.rcvif), if_name(rt->rt_ifp)); 349 } 350 if (mcopy) 351 icmp6_error(mcopy, ICMP6_DST_UNREACH, 352 ICMP6_DST_UNREACH_BEYONDSCOPE, 0); 353 m_freem(m); 354 return; 355 } 356 357 if (m->m_pkthdr.len > rt->rt_ifp->if_mtu) { 358 in6_ifstat_inc(rt->rt_ifp, ifs6_in_toobig); 359 if (mcopy) { 360 u_long mtu; 361 #ifdef IPSEC_IPV6FWD 362 struct secpolicy *sp; 363 int ipsecerror; 364 size_t ipsechdrsiz; 365 #endif 366 367 mtu = rt->rt_ifp->if_mtu; 368 #ifdef IPSEC_IPV6FWD 369 /* 370 * When we do IPsec tunnel ingress, we need to play 371 * with if_mtu value (decrement IPsec header size 372 * from mtu value). The code is much simpler than v4 373 * case, as we have the outgoing interface for 374 * encapsulated packet as "rt->rt_ifp". 375 */ 376 sp = ipsec6_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, 377 IP_FORWARDING, &ipsecerror); 378 if (sp) { 379 ipsechdrsiz = ipsec6_hdrsiz(mcopy, 380 IPSEC_DIR_OUTBOUND, NULL); 381 if (ipsechdrsiz < mtu) 382 mtu -= ipsechdrsiz; 383 } 384 385 /* 386 * if mtu becomes less than minimum MTU, 387 * tell minimum MTU (and I'll need to fragment it). 388 */ 389 if (mtu < IPV6_MMTU) 390 mtu = IPV6_MMTU; 391 #endif 392 icmp6_error(mcopy, ICMP6_PACKET_TOO_BIG, 0, mtu); 393 } 394 m_freem(m); 395 return; 396 } 397 398 if (rt->rt_flags & RTF_GATEWAY) 399 dst = (struct sockaddr_in6 *)rt->rt_gateway; 400 401 /* 402 * If we are to forward the packet using the same interface 403 * as one we got the packet from, perhaps we should send a redirect 404 * to sender to shortcut a hop. 405 * Only send redirect if source is sending directly to us, 406 * and if packet was not source routed (or has any options). 407 * Also, don't send redirect if forwarding using a route 408 * modified by a redirect. 409 */ 410 if (rt->rt_ifp == m->m_pkthdr.rcvif && !srcrt && 411 (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0) 412 type = ND_REDIRECT; 413 414 #ifdef IPV6FIREWALL 415 /* 416 * Check with the firewall... 417 */ 418 if (ip6_fw_chk_ptr) { 419 u_short port = 0; 420 /* If ipfw says divert, we have to just drop packet */ 421 if ((*ip6_fw_chk_ptr)(&ip6, rt->rt_ifp, &port, &m)) { 422 m_freem(m); 423 goto freecopy; 424 } 425 if (!m) 426 goto freecopy; 427 } 428 #endif 429 430 #ifdef OLDIP6OUTPUT 431 error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, 432 (struct sockaddr *)dst, 433 ip6_forward_rt.ro_rt); 434 #else 435 error = nd6_output(rt->rt_ifp, m, dst, rt); 436 #endif 437 if (error) { 438 in6_ifstat_inc(rt->rt_ifp, ifs6_out_discard); 439 ip6stat.ip6s_cantforward++; 440 } else { 441 ip6stat.ip6s_forward++; 442 in6_ifstat_inc(rt->rt_ifp, ifs6_out_forward); 443 if (type) 444 ip6stat.ip6s_redirectsent++; 445 else { 446 if (mcopy) 447 goto freecopy; 448 } 449 } 450 if (mcopy == NULL) 451 return; 452 453 switch (error) { 454 case 0: 455 #if 1 456 if (type == ND_REDIRECT) { 457 icmp6_redirect_output(mcopy, rt); 458 return; 459 } 460 #endif 461 goto freecopy; 462 463 case EMSGSIZE: 464 /* xxx MTU is constant in PPP? */ 465 goto freecopy; 466 467 case ENOBUFS: 468 /* Tell source to slow down like source quench in IP? */ 469 goto freecopy; 470 471 case ENETUNREACH: /* shouldn't happen, checked above */ 472 case EHOSTUNREACH: 473 case ENETDOWN: 474 case EHOSTDOWN: 475 default: 476 type = ICMP6_DST_UNREACH; 477 code = ICMP6_DST_UNREACH_ADDR; 478 break; 479 } 480 icmp6_error(mcopy, type, code, 0); 481 return; 482 483 freecopy: 484 m_freem(mcopy); 485 return; 486 } 487
Indexes created Thu Sep 25 08:09:54 GMT 2025